Regio- and stereoselective 1(S)-camphorsulfonylation of monoalkoxycalix[4]arenes
摘要:
The reaction of calix[4]arene monoalkyl ethers with 1(S)-camphor-10-sulfonyl chloride yields 1,2- or 1,3-alkoxy-1(S)-camphorsulfonyloxycalixarenes depending on the nature of the base used. In the presence of triethylamine only 1,3-substituted derivatives are formed. Two diastereomers of the 1,2-substituted calixarenes with clockwise and anticlockwise arrangement of alkyl and camphorsulfonyl groups at the narrow rim are formed in the presence of sodium hydride or potassium carbonate. Due to chiral induction of the camphorsulfonyl group the 1,2-substitution is diastereoselective. The ratio of diastereomers formed is dependent on the alkyl groups at the calixarene narrow rim. (C) 2008 Published by Elsevier Ltd.
The reaction of calix[4]arene monoalkyl ethers with 1(S)-camphor-10-sulfonyl chloride yields 1,2- or 1,3-alkoxy-1(S)-camphorsulfonyloxycalixarenes depending on the nature of the base used. In the presence of triethylamine only 1,3-substituted derivatives are formed. Two diastereomers of the 1,2-substituted calixarenes with clockwise and anticlockwise arrangement of alkyl and camphorsulfonyl groups at the narrow rim are formed in the presence of sodium hydride or potassium carbonate. Due to chiral induction of the camphorsulfonyl group the 1,2-substitution is diastereoselective. The ratio of diastereomers formed is dependent on the alkyl groups at the calixarene narrow rim. (C) 2008 Published by Elsevier Ltd.